Apparatus for developing exposed diazotype sheet material in which an accurately metered amount of liquid developer is applied to the sheet material by an applicator roller. The roller surface is essentially smooth and liquid developer is applied to the roller surface in an amount metered by a metering blade assembly which includes a flexible support member carrying a resilient backing layer which, in turn, carries a fine mesh screen held in contact with the smooth surface of the roller. The scr...

A heat-developable diazotype sheet containing an acid-stabilized diazonium salt in one layer thereof and an acid-neutralizing component in another layer thereof is shown wherein at least 25% by weight of the acid-neutralizer component comprises imidazole derivatives of a specific formula.

In an apparatus for producing from a developer solution a gaseous developer medium for diazotype materials, which apparatus includes an inclined surface for passing the developer solution through a vaporizing region from a first end to a second end thereof, heater elements disposed along the vaporizing region, the temperature in the region of the second end being at least 25.degree. C higher than the temperature in the region of the first end and the temperature increasing with the distance from...

An erasable diazotype intermediate assembly comprising a translucent paper base, a rubber-like polymeric intervening barrier layer and a sensitizing layer consisting of a water soluble cellulose derivative, a cross linking resin and the diazo sensitizing chemicals.

A diazotype material, which comprises a supported light-sensitive layer comprising a light-sensitive, water-insoluble diazoimino compound of the formula: ##STR1## wherein R is an aryl group and R.sub.1 and R.sub.2 are organic radicals, which may be the same or different, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are attached form a heterocyclic group, an azo coupler, and an alkaline material, said diazoimino compound, when exposed to ultraviolet light, being reactive w...

Plastic pigment spheric particles which form a matrix for diazotype reproduction materials are applied to a base sheet. Whether the diazo sensitizing solution is included in admixture with spheric plastic pigment particles or is applied thereafter as a second coating, a matrix is formed having a sensitized diazo layer dispersed throughout. Such diazo matrices permit control of contrast ratios over a wide range. Also such diazo matrices are transferable. The diazo matrix image can be made water f...

Apparatus for developing exposed diazotype sheet material in which an accurately metered amount of liquid developer is applied to the sheet material by an applicator roller. The roller surface is essentially smooth and liquid developer is applied to the roller surface in an amount metered by a metering blade assembly which includes a flexible support member carrying a resilient backing layer which, in turn, carries a fine mesh screen held in contact with the smooth surface of the roller. A sheet...

Diazotype systems and method of diazotype reproduction are provided, the systems including as the coupler compound an imidazole coupler having the formula; ##SPC1## Wherein R.sub.1 is a hydrogen atom or an alkyl radical; R.sub.2 is a hydrogen atom, an alkyl radical, a thioalkyl radical, a sulfamido radical, a carbonylamino radical or an aryl radical; and R.sub.3 and R.sub.4 can be the same or different and are selected from the group consisting of a hydrogen atom, a carbonyl amino radical, an al...

A diazotype reproduction material is a fibrous paper base having at least one overcoat, which is an acidic diazotype layer and a layer strata below the overcoat containing an anionic compound to minimize deep penetration of diazotype diazonium salts.

Diazotypes with new yellow coupler with an active methylene group are disclosed; the couplers do not migrate and excel by their relatively reduced coupling speed for greatly improved shelf life of diazotypes. In preferred embodiments the improved new diazotypes contain acetoacetoxyethyl methacrylate or acrylate as yellow coupler.